• Carbon letters
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• 제11권2호
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• pp.117-121
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• 2010

The composites of alginate, carbon nanotube, and iron(III) oxide were prepared for the removal of heavy metal in aqueous pollutant. Both alginate and carbon nanotube were used as an adsorbent material and iron oxide was introduced for the easy recovery after removal of heavy metal to eliminate the secondary pollution. The morphology of composites was investigated by FE-SEM showing the carbon nanotubes coated with alginate and the iron oxide dispersed in the alginate matrix. The ferromagnetic properties of composites were shown by including iron(III) oxide additive. The copper ion removal was investigated with ICP AES. The copper ion removal efficiency increased greatly over 60% by using alginate-carbon nanotube composites.

• Journal of Magnetics
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• 제6권4호
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• pp.129-131
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• 2001

In order to investigate the effect of the interface on GMR, [NiFe(25 ${\AA}$)/Cu(24${\AA}$)]$_2$/Si thin film was epitaxially grown on HF-treated Si (001) substrate using a DC magnetron sputtering method. Typical GMR effects could be observed in epitaxial film with a weak antiferromagnetic exchange coupling while non epitaxial film showed unsaturated and broad MR curves probably due to inter-diffusion between NiFe and Cu layers. Ferromagnetic resonance (FMR) experiment showed two distinct absorption peaks in all films. Each peak was revealed to come from each NiFe layer with different magnetic property. In FMR measurement very clear interface in epitaxial films could be confirmed by a lower value of line width (ΔH) and higher M$\sub$s/ of epitaxial film than those of non epitaxial films, respectively.

• 한국산학기술학회논문지
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• 제5권5호
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• pp.395-402
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• 2004

보석용 다이아몬드의 기술발전에 따라 고온고압법으로 만들어진 합성다이아몬드 인지, 또는 고온고압법(high temperature high pressure:HTHP)으로 향상처리된 천연다이아몬드 인지의 여부를 처리하지 않은 천연다이아몬드와 비교하여 명확히 확인할 필요가 있다. 본 연구에서는 합성다이아몬드를 진동시편자력계를 이용하여 강자성 특성을 보이는 경우 합성다이아몬드로 감별하는데 성공하였다. 또한 HTHP 향상처리 된 TypeIa, TypeIIa 다이아몬드를 FTIR(Fourier Transform Infrared) 분광기를 이용하여 HTHP 처리 공정 전후의 스펙트럼 분석으로 감별할 수 있음을 확인하였다.

• Journal of Magnetics
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• 제16권1호
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• pp.6-9
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• 2011

Spin-motive force has drawn attention because it contains a fundamental physical property. Spin-motive force creates effective electric and magnetic fields in moving magnetization; a vortex is a plausible system for observing the spin-motive force because of the abrupt profile of magnetization. However, the time-averaged value of a spin-motive force becomes zero when a vortex core undergoes gyroscopic motion. By means of micromagnetic simulation, we demonstrates that a non-zero time-averaged electric field induced by spin-motive force under certain conditions. We propose an experimental method of detecting spin-motive force that provides a better understanding of spin transport in ferromagnetic system.

• 열처리공학회지
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• 제34권1호
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• pp.10-16
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• 2021

Exhaust manifold is a very important component that is directly connected to air environment pollution and that requires strict mechanical properties such as high temperature fatigue and oxidation. Among stainless steels, the ferritic stainless steel with body-centered cubic structure shows excellent resistance of stress-corrosion cracking, ferromagnetic at room temperature, very excellent cold workability and may not be enhanced by heat treatment. The microstructural characteristics of four cast ferritic stainless steels which are high heat-resistant materials, were analyzed. By comparing and evaluating the mechanical properties at room temperature and high temperature in a range of 400℃~800℃, a database was established to control and predict the required properties and the mechanical properties of the final product. The precipitates of cast ferritic stainless steels were analyzed and the high-temperature deformation characteristics were evaluated by comparative analysis of hardness and tensile characteristics of four steels at room temperature and from 400℃ to 800℃.

• 한국세라믹학회지
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• 제40권5호
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• pp.428-433
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• 2003

이 연구에서는 소결온도와 Zr치환에 따른 아이솔레이터/서클레이터용 YIG 페라이트의 미세구조와 전자기적 특성의 변화를 고찰하고자 하였다. 조성은 $Y_{2.1}$C $a_{0.9}$F $e_{4.4-x}$ $V_{0.5}$I $n_{0.05}$A $l_{0.05}$Z $r_{x}$ $O_{12}$에서 x의 값을 0, 0.05, 0.1, 0.2로 변화시켰으며, 일반적인 세라믹 제조 공정으로 YIG페라이트를 제조하였다. 그 결과, Zr이 0.1 mol 정도 치환된 YIG 페라이트가 가장 높은 포화자화(1097 gauss) 값을 나타내었으며, 또한, Zr을 0.2 mol 치환한 경우 격리도 18.60 dB, 삽입손실 0.45 dB의 마이크로파 특성을 나타내었다. 자기 공명 선폭($\Delta$H)은 Zr의 치환량이 증가할수록 감소하는 경향을 보였다.다.다.다.

• Journal of Magnetics
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• 제17권2호
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• pp.86-95
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• 2012

This study investigated the effects of adding a third alloying element, Ni, to create $Fe_{70-x}Pd_{30}Ni_x$ (x = 2, 4, 6, 8 at.% Ni) ferromagnetic shape memory alloys (FSMAs). The Ni replaced a portion of the Fe. The $Fe_{70-x}Pd_{30}Ni_x$ alloys were homogenized through hot and cold forging to gain a ~38% reduction in thickness, next they were solution-treated (ST) with annealing recrystallization at $1100^{\circ}C$ for 8 h and quenched in ice brine, and then aged at $500^{\circ}C$ for 100 h. Investigation of the microstructures and magnetostriction indicated that the greater Ni amount in the $Fe_{70-x}Pd_{30}Ni_x$ alloys reduced saturation magnetostriction at room temperature (RT). It was also observed that it was more difficult to generate annealed recrystallization. However, with greater Ni addition into the $Fe_{70-x}Pd_{30}Ni_x$ (x = 6, 8 at.% Ni) alloys, the $L1_0+L1_m$ twin phase decomposition into stoichiometric $L1_0+L1_m+{\alpha}_{bct}$ structures was suppressed after the $500^{\circ}C$/100 h aging treatment. The result was that the $Fe_{70-x}Pd_{30}Ni_x$ (x = 6, 8 at.% Ni) alloys maintained a high magnetostriction and magnetostrictive susceptibility (${\Delta}{\lambda}{_\parallel}{^s}/{\Delta}H$) after the alloys were aged at $500^{\circ}C$ for 100 h. This magnetic property of the $Fe_{70-x}Pd_{30}Ni_x$ (x = 6, 8 at.% Ni) alloys make it suitable for application in a high temperature (T > $500^{\circ}C$) and high frequency environments.

• 대한화학회지
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• 제54권6호
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• pp.766-770
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• 2010

본 연구는 전이금속이 치환된 묽은 자성 반도체의 자기적 특성을 연구하였다. 울츠자이트(wurtzite) 구조를 가지는 화합물은 졸-겔(sol-gel)법을 이용하여 합성하였다. 열역학적 특성과 자기적 특성을 가진 $Zn_{1-x}Co_xO$은 단일상으로 나타났으며, 농도에 따라 다른 특성을 보여주었다. 묽은 자성 반도체의 특성을 조사하기 위해 X-ray diffraction (XRD), scanning electronic microscope (SEM) 및 vibrating sample magnetometer (VSM)을 사용하였다. 구조 분석을 통해 단일상이 확인된 시료에서는 모두 강자성 특성이 발견되었고, 전이금속 이온의 농도를 5%이상 치환이 되면 강자성이 감소하는 현상이 나타났다.

• 한국재료학회지
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• 제11권12호
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• pp.1042-1046
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• 2001

Co-22%Cr alloy films are promising for high-density perpendicular magnetic recording media with their perpendicular anisotropy and large coercivity of 3000 Oe. We observed that a self organized nano structure(SONS) of fine ferromagnetic Co-enriched phase and paramagnetic Cr-enriched phase appears inside the grain of Co-Cr magnetic alloy thin films at the elevated substrate temperature after do-sputtering. We prepared 1000 $\AA$-thick Co-22%Cr films on 2000 $\AA$- SiO$_2$/Si(100) substrates at the deposition rate of 100 $\AA$/min with substrate temperatures of 3$0^{\circ}C$, 10$0^{\circ}C$, 15$0^{\circ}C$, 20$0^{\circ}C$, 30$0^{\circ}C$, and 40$0^{\circ}C$, respectively. We employed a vibrating sample magnetometer(VSM) to measure the B-H loops showing the saturation magnetifation, coercivity, remanence in in- plane and out- of- plane modes. In- plane coercivity, perpendicular coercivity, and perpendicular remanence increased as substrate temperature increased, how-ever they decreased after 30$0^{\circ}C$ slowly. Transmission electron microscope (TEM) characterization revealed that the self organized nano structure (SONS) appears at the elevated substrate temperature, which forms fine Co-enriched phases inside a grain, then it eventually affect the perpendicular magnetic property. Our results imply that we may tune the perpendicular magnetic properties with SONS obtained at appropriate substrate temperature.

• 한국자기학회지
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• 제23권3호
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• pp.98-103
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• 2013

NiFe/Cu/NiFe/IrMn/NiFe/Cu/NiFe 이중 거대자기저항-스핀밸브(GMR-SV) 박막의 진공 후열처리 온도의존성을 조사하여 강자성층 자화용이축을 유도하였다. 자유층과 고정층의 자화용이축에 의존하는 이중 스핀밸브 박막의 자기저항곡선은 외부자기장 각도를 다르게 하면서 측정하였다. 열처리온도가 $105^{\circ}C$일 때, $0^{\circ}$와 $90^{\circ}$ 사이 임의 측정 각도에서 약 2.0 %/Oe인 자장감응도 특성을 얻었다. 이러한 결과는 면상 강자성층과 자유층을 면상에서 서로 직교한 자화방향 유도를 통하여 이중구조 GMR-SV 박막이 고감도 바이오센서로 사용할 가능성을 제시하였다.